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Definition

A degenerative opacity of the lens that leads to loss of vision.

Clinical Signs

May observe the following:

• Initially be seen as a white dot behind pupil.
• Progression of a gray or milky white discoloration of the pupil(s).

Etiology

Cataracts, a white/gray discoloration of the pupil(s), can occur due to trauma, inflammation, systemic disease, and aging.

They are typically bilateral, but may progress more in one eye than the other.

A transient form of cataracts has been know to happen frequently in rodents when they are placed under anesthesia. It is believed to be due to the changing composition and temperature of the aqueous humor of the eye while open and unblinking. This does resolve once the animal recovers.²

Cataracts occurring with age may be due to changes in protein, accumulation of water and edema, and the disruption of normal fibers in the lens.

As the condition of the cataracts advance, it causes the lens to become cloudy which leads to blindness.

There can also be other causes that can contribute to the early formation of cataracts, such as long term use of corticosteroids or phenothiazines, or diseases such as diabetes, microphthalmia, and hypertension.

Figures

Case Histories of Cataract Formation

• Fig. 1: Cataracts and case history
• Fig. 2: Cataracts in hairless rat.
• Fig. 3  Case history of cataract in 20 month old Siamese rat.
• Cataracts  Visit Lisa Jenny’s page for photo of rat showing initial cataracts.

Diagnostics

Visualized by ophthalmoscopy

Treatment

Rats, having poor vision to start with, adapt well. Treatment should be directed at correcting underlying conditions if possible.

Nursing Care

• Provide for safe environment. Reduce chances of falls from heights by keeping cage levels to a minimum.
• Allow the rat to become familiar with cage surroundings. Prevent redesigning or moving interior cage accessories around.
• Keep water bottles and food dishes in same familiar area of cage.

Outcome

• Underlying conditions corrected.
• No advancement of condition noted.

Prevention

• Early treatment of conditions or illnesses associated with the formation of cataracts may prevent or delay their onset.

Posted on June 28, 2003, 09:59, Last updated on April 28, 2009, 13:18 | Eyes